Answer:
800 children’s ticket were sold and 400 adult tickets were sold
Step-by-step explanation: using elimination
variables-
amount of children’s ticket sold: C
amount of adult tickets sold: A
equations-
A+C=1200
5A+11C=10,800
solving-
(A+C=1200) -5 —> -5A-5C=-6000
5A+11C= 10,800
use elimination on those two equation and you get C=800, A=400.
to check you plug in the numbers into one of the equations, doesn’t matter which one.